Stretchable nonwoven fabrics and method for producing same

Abstract

A stretchable nonwoven fabric is provided, in which a uniform web comprising 70 to 100% by weight of polypropylene base heat-bondable composite fibers and 0 to 30% by weight of other organic fibers and having a web heat shrinking percentage "A" of 50% or lower at 100° C. and a web heat shrinking percentage "B" of 50% or higher at 120° C. provided that a difference "B"-"A" between the latter and the former is 20% or higher, the fibers being uniformly entangled together, has been shrinked as a result of sufficient crimping and more increased entanglement of the above composite fibers imparted through further heat-treatment, and which has an elastic recovery-at-30%-elongation of 80% or higher in both the warp and weft directions. This nonwoven fabric has no density variation, no crease, and excellent stretchability.

What is claimed is: 
     
       1. A stretchable nonwoven fabric formed from a hydro-entangled uniform web comprising 70 to 100% by weight of polypropylene base heat-bondable composite fibers and 0 to 30% by weight of other organic fibers and having a heat shrinking percentage "A" of 50% or lower at 100° C. and a heat shrinking percentage "B" of 50% or higher at 120° C. provided that the difference "B"-"A" between the later and the former is 20% or higher, said fibers being crimped and uniformly entangled as a result of crimping and increased entanglement of the above composite fibers resulting from said web having had hot air at a temperature greater than 120° C. and less than the melting point of the high melting component of said composite fibers blown on the front and back sides thereof alternately and successively, said stretchable nonwoven fabric having an elastic recovery-at-30%-elongation of 80% or higher in both the warp and waft directions. 
     
     
       2. A stretchable nonwoven fabric as claimed in claim 1, in which said composite fibers are heat-bonded together at their portions of contact with one another. 
     
     
       3. A method for producing stretchable nonwoven fabric, which comprises: subjecting to a water needle technique a uniform web comprising 70 to 100% by weight of polypropylene base heat-bondable and heat-crimpable composite fibers and 0 to 30% by weight of other organic fibers and having a web heat shrinking percentage "A" of 50% or lower at 100° C. and a web heat shrinking percentage "B" of 50% or higher at 120° C. with the proviso that a difference "B"-"A" between the latter and the former is 20% or higher, to uniformly entangle together said fibers, and   delivering the thus obtained web, in which the fibers have been hydro-entangled, with no tension applied thereon, while hot air is blown on the front and back sides thereof alternately and successively, the temperature of said hot air being between 120° C. and lower than the melting point of the high-melting component of said heat-bondable composite fibers, thereby further heat-treating said composite fibers to impart sufficient crimping and more increased entanglement thereto for the purpose of shrinking said web.   
     
     
       4. A method for producing stretchable nonwoven fabric as claimed in claim 3, wherein said composite fibers are heat-bonded together at their portions of contact with one another by using hot air of a temperature higher than the melting point of a low-melting component of said heat-bondable composite fibers.